I have been using J&M Machining for years, and have had them build a few engines for me. They are doing a 1934 Master engine for me right now. I have always found them to be very fair on their prices, very professional, very well equipped. I always make sure to ask them what the cost will be when adding anything to the workscope. They do all work in-house, including regrinding cams and cranks, re-babbiting, line boring, crack testing, balancing. I've never had any problems with them, and consider them to be the best in the business.
Just be sure to understand what each task costs up front, when you add workscope to the job.